(1) Field of the Invention
The present invention relates to a method for continuity test of integrated circuit. More particularly, the present invention relates to a method for continuity test of integrated circuit by utilizing current flow.
(2) Prior Art
Integrated circuit (IC) is a device which is formed a complete and logical circuit by integrating several electronic devices, such as transistor, electrostatic discharge device (ESD), and capacitor etc., on a silicon chip. Integrated circuits could have several abilities of function, such as control, calculate, and memory etc., for applying varies of electronic products. Fabrication process of integrated circuit includes design, pulling, slicing, polishing, oxidation, diffusion, deposition, mask, etching, detection, die saw, die bonding, wire bonding, package, test process etc. In these processes, the test process is to test several characteristics of integrated circuit, such as electricity of the integrated circuit, for making sure quality of the integrated circuit. Thus, it's why the test process is a very important process in the fabrication process of integrated circuit.
FIG. 1 shows a traditional method for testing open circuit of integrated circuit. The method includes a direct circuit (DC) flowed to a device under test (DUT) 101 for measuring voltage of the DUT and judging quality of continuity of the DUT 101. As shown in FIG. 1, a current is inputted to the DUT 101 by a first pin 102 of the DUT 101, and is outputted from a second pin 103 of the DUT 101. After the test process, the differential voltage between the first pin 102 and the second pin 103 are measured. Test results of the test process are judged by the differential voltage. When the differential voltage is a value between 0.3 volts to 1.5 volts, the test result of the DUT is acceptable and shown pass for reference. Otherwise, outside the mentioned-above ranges, the test result of the DUT is unacceptable and shown fail for reference.
As shown in FIG. 1, the differential voltage between the first pin 102 and the second pin 103 is the same as a differential voltage through an ESD device 104. When applying a current, 100 μA, to the ESD device 104 which has a contact resistance 105 is 900Ω, the tested voltage, only adding 0.09 volts, is obtained. Then, the adding value of tested voltage of the DUT tested by mentioned-above method would be judged pass for reference. However, a DUT having a 900Ω contact resistance would make the DUT be judged being abnormal when functional test of the DUT is performed.
Therefore, in the conventional method for testing open circuit of integrated circuit, the contact resistance 105 of the DUT couldn't be measured. Then, the whole quality of the DUT would be affected by judging error. Thus, a method for integrated circuit test is needed to solve the problem which the contact resistance of the DUT couldn't be measured by the traditional method for testing open circuit of integrated circuit. Moreover, the improving method is needed to measure a contact resistance of the DUT accurately for making sure the quality of the DUT.